The present invention relates to a reamer for boring an inner peripheral surface of a hole provided in a work, and to a method of using the reamer.
When, for example, an inner peripheral surface of a cylinder bore defined in a cylinder block of an engine is subjected to boring, a reamer 01 as shown in FIG. 6 is used in the prior art. The reamer 01 has a head 03 at a tip end of a shank 02, and five cutting tools 04 are supported circumferentially at equal distances on the head. Thus, the inner peripheral surface of the cylinder bore B in the cylinder block W is cut by the cutting tools 04 by moving the reamer 01 along its axis Lt, while rotating the reamer 01 about its axis Lt.
The above prior art reamer suffers from a problem that since it is necessary to move the reamer 01 axially by a distance D in order to cut the inner peripheral surface of the cylinder bore B having a depth D, it is difficult to reduce the time of working.
The present invention has been accomplished with the above circumstances in view, and it is an object of the present invention to reduce the time of working when boring an inner peripheral surface of a hole in a work.
To achieve the above object, according to the present invention, there is proposed a reamer for boring an inner peripheral surface of a hole provided in a work, comprising a plurality of chip groups each having a plurality of chips disposed circumferentially on a circle having a diameter smaller than an inside diameter of the hole in the work, the chip groups being disposed axially at a given pitch around outer peripheral surfaces of substantially columnar heads wherein each circle passing through tip ends of cutting edges of each of the chip groups has a diameter set equal to each other.
With the above arrangement, the plurality of chip groups which are disposed axially at the given pitch simultaneously cut the inner peripheral surface of the hole in the work. Therefore, the inner peripheral surface of the hole in the work can be cut over the entire length of the hole only by moving the reamer axially by the distance corresponding to one pitch, thereby enabling the time required for the boring work to be reduced. In addition, the diameter of the hole made by boring can be changed by changing the diameter of a circle of eccentric movement of the axis of the reamer, and hence, the general-purpose utility of the reamer can be enhanced.
According to the present invention, there is proposed a process for use of a reamer of the above-described type, comprising a step of inserting at least two chip groups into a hole in a work with an axis of the reamer aligned with an axis of the hole in the work, a step of moving the reamer in the direction of pulling from the hole in the work by the distance equal to the pitch, while moving the axis of the rotated reamer circumferentially on a circle about the axis of the hole, and a step of pulling the reamer fully out of the hole in the work with the axis of the reamer aligned with the axis of the hole in the work.
With the above arrangement, when the axis of the reamer is moved circumferentially on the circle about the axis of the hole while rotating the reamer, after the reamer is inserted into the hole in the work, the plurality of chip groups simultaneously cut the inner peripheral surface of the hole. When the reamer is moved in the direction of pulling from the hole by the distance equal to one pitch in this state, the plurality of chip groups simultaneously cut the inner peripheral surface of the hole in the work by the distance equal to one pitch, and hence, the boring work can be completed in a short time. In addition, the diameter of the hole made by boring can be changed by changing the diameter of the circle of eccentric movement of the axis of the reamer and hence, the general-purpose properties can be enhanced.